Why an I getting this error? android.os.NetworkOnMainThreadException
Why does this throw a network on main thread exception? its on an async task
class JS extends AsyncTask<StringBuilder, Void, String>{
@Override
protected String doInBackground(StringBuilder... urlBuilder) {
try {
URL url = new URL(urlBuilder[0].toString());
HttpURLConnection client = (HttpURLConnection) url.openConnection();
client.setRequestProperty("accept", "application/json");
InputStream in = client.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String returnString = br.readLine();
client.disconnect();
return returnString;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
EDIT:
Full Code:
package oliver; import android.os.AsyncTask; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.json.JSONTokener; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; import java.util.ArrayList; import java.util.Date; import java.util.List; public class DrinkOrDriveWebService { private final static String DRINK_OR_DRIVE_WEB_SERVICE = "http://idrivedjango-env-qrs5vkxvvi.elasticbeanstalk.com/api/"; /** * Constructor */ List listOfBarUsers; List listOfPartyUsers; List listOfParties; List listOfPromotions; public static JS j = new JS(); public DrinkOrDriveWebService() { listOfBarUsers = new ArrayList(); listOfPartyUsers = new ArrayList(); listOfParties = new ArrayList(); listOfPromotions = new ArrayList(); } public void parseBarUsers() { // CPSC 210 Students: You will need to complete this method // builds the URL to initialize session in the Waldo API StringBuilder urlBuilder = new StringBuilder(DRINK_OR_DRIVE_WEB_SERVICE); urlBuilder.append("/baruser/"); String input = j.doInBackground((urlBuilder)); JSONArray obj; try { // parses the name, location, lat, lon, and timestamp of each Waldo generated obj = (JSONArray) (new JSONTokener(input).nextValue()); System.out.println(obj.toString()); if (obj.length() != 0) { // For all Waldos generated for (int i = 0, var = obj.length(); i getPartyUsers() { return this.listOfPartyUsers; } public List getBarUsers() { return this.listOfBarUsers; } public List getParties() { return this.listOfParties; } public List getPromos() { return this.listOfPromotions; } /** * Return the current list of Waldos that have been retrieved * * @return The current Waldos */ /** * Retrieve messages available for the user from the Waldo web service * * @return A list of messages */ /** * Execute a given query * * @param urlBuilder The query with everything but http: * @return The JSON returned from the query */ } class JS extends AsyncTask{ @Override protected String doInBackground(StringBuilder... urlBuilder) { try { URL url = new URL(urlBuilder[0].toString()); HttpURLConnection client = (HttpURLConnection) url.openConnection(); client.setRequestProperty("accept", "application/json"); String returnString = client.getResponseMessage(); client.disconnect(); return returnString; } catch (Exception e) { e.printStackTrace(); } return null; } }
LogCat :
03-16 11:01:27.375 23401-23401/com.example.untitled4 W/System.err﹕ android.os.NetworkOnMainThreadException
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at java.net.InetAddress.getAllByName(InetAddress.java:214)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.Dns$1.getAllByName(Dns.java:28)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:216)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:122)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:292)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpEngine.sendSocketRequest(HttpEngine.java:255)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:206)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:345)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:296)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponseMessage(HttpURLConnectionImpl.java:499)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at oliver.JS.doInBackground(DrinkOrDriveWebService.java:288)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at oliver.DrinkOrDriveWebService.parseParty(DrinkOrDriveWebService.java:146)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.example.untitled4.mthr.doInBackground(mthr.java:20)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.example.untitled4.MyActivity.register(MyActivity.java:75)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.example.untitled4.MyActivity$1.onClick(MyActivity.java:51)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.view.View.performClick(View.java:4438)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.view.View$PerformClick.run(View.java:18422)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:733)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:95)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.os.Looper.loop(Looper.java:136)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5017)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:515)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
03-16 11:01:27.385 23401-23401/com.example.untitled4 D/AndroidRuntime﹕ Shutting down VM
03-16 11:01:27.385 23401-23401/com.example.untitled4 W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4194bba8)
You are invoking the async task the wrong way:
String input = j.doInBackground((urlBuilder));
You should not be calling doInBackground()
yourself. Instead, create a new instance of the async task class object and call execute()
on it. Capture the results back to UI thread in onPostExecute()
.
For more information regarding NetworkOnMainThreadExecption. Refer this question
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